Hi David,
I’m personally VERY excited by Blender. This is a fully featured 3D modelling and animation app that’s completely free: https://www.blender.org/
There’s a forum for it right here on the COW. Too early to tell if there will be any integration with FCP X or Motion 5, but there are scripts for sending Blender layers to After Effects.
It has very basic video editing (no jokes please!) and a decent node-based compositor. There’s a vibrant community and a number of third party manuals.
Ian